If there is no name argument given, OmniAuth will try to guess the name
by the class name. In
OmniAuth::Strategies::OpenIDConnect gets translated to
This leads to an immediate 404 error after clicking the login button because OmniAuth can't match the current route (/users/auth/openid_connect) against the expected one (/users/auth/openidconnect).
Other providers, such as Google OAuth2, set this name as the default option within the OmniAuth Strategy. Until a fix is merged upstream, let's just set the parameter ourselves.